This invention relates to an antenna system for receiving signals that are transmitted by a geostationary satellite, of a type comprising a reflector, a source device and a device for treating the signals received by the source device.
In order that geostationary satellites are able to remain as long as possible in their initial position, they are equipped with embarked means that are adapted for correcting their deviations from this position, the antenna being a fixed antenna. Yet, after a certain working time, power of these embarked means becomes too small for avoiding satellite deviations and a movement of the satellite in an inclined orbital path. Consequently, the quality of the signals received by the antenna is progressively reduced and, finally, the satellite becomes unusable.
The purpose of the present invention is to provide an antenna system which will be able to considerably extend the duration time during which the antenna can correctly receive the signals that are transmitted by the satellite.
For reaching this purpose, the antenna system according to the invention comprises means for automatically tracking the satellite that deviates from its initial position to an inclined orbital path.
According to a feature of the invention, these tracking means comprise a plurality of individual sources arranged at a predetermined distance the one from the other in a vertical plane that contains the antenna focal point, in order to create a multiplicity of overlapping main beams.
According to another feature of the invention, the number of individual sources and the distance therebetween are dependent on the aperture height of the antenna and on the extent of desired vertical tracking.
According to another feature of the invention, among the plurality of individual sources, it is the source that produces the greatest output signal which is connected to the device for treating the signals transmitted by the satellite.
According to another feature of the invention, the source device comprises means for detecting the source that produces the greatest output signal.
Having briefly described the essential features of the present invention, the following drawings together with the more detailed description will serve to explain the concepts and principles of the invention.